Sheet metal brake



Dec. 2, 1969 H. c. BARNACK SHEET METAL BRAKE 5 Sheets-Sheet 1 Filed June 19, 1967 INVENTOR.

H ENRY C. BARNACK D 1969 H. c. BARNACK 3,481,174

SHEET METAL BRAKE Filed June 19, 1967 :s Shets-Sheet 2 INVENTOR v HENRY c. BARNACK A TTCZQ/VEY Dec. 2, 1969 H, c. BARNACK 3,481,174

SHEET MEIITAL BRAKE Filed June 19, 1967 3 Sheets-Sheet :5

fIE- 4; TIE- El INVENTOR.

HENRY QBARNACK BY @wad @13 ATTORNEY United States Patent 3,481,174 SHEET METAL BRAKE Henry C. Barnack, 126 Craiwell Ave., West Springfield, Mass. 01089 Filed June 19, 1967, Ser. No. 646,963 Int. Cl. B21d 11/04 U.S. Cl. 72-319 6 Claims ABSTRACT OF THE DISCLOSURE A brake for bending sheet metal comprising, a frame having a fixed jaw and a movable jaw; an anvil member adjustably secured to the fixed jaw; the movable jaw having a clamping surface movable between workpiece clamping and non-clamping positions relative to the anvil member; means for releasably locking the movable jaw in workpiece clamping position; a bending member hingedly connected to the fixed jaw; and a spring-loaded floatable compensator pivoted to the bending member and having a surface bearing on the workpiece.

BACKGROUND OF THE INVENTION Field of the invention Apparatus for bending sheet metal wherein the workpiece is clamped between a pair of jaws and a bending member hinged to one of the jaws bears against the workpiece to bend it into the desired angular shape.

Description of the prior art Brakes of the prior art have been expensive in their manufacture, cumbersome and complicated in their structure, unreliable in their use, usually seriously mar or scratch the workpiece in the area of the bend, and are unable to accept workpieces having a preformed bead or flange.

SUMMARY OF THE INVENTION The invention provides a portable, light-weight, inexpensive brake which is easy to transport and set up, which is extremely reliable and versatile in its use, and which will not mar or scratch the surface of the workpiece in the area of the bend The invention provides a brake which will accept either flat sheet .metal stock or stock which has been provided with a preformed bead or flange.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a brake embodying the invention;

FIG. 1A is a fragmentary view in perspective of a modified form of handle means for the brake;

FIG. 2 is an enlarged, fragmentary end elevational view showing the brake in .work clamping position, with portions of the brake broken away for clarity;

FIG. 3 is a fragmentary view similar to FIG. 2 showing the action of the brake clamping member in its movement between non-clamping and clamping positions;

FIGS. 4 and 5 are fragmentary views similar to FIG. 3 showing the action of the several bending bar components during the bending of a workpiece.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The brake is so organized and designed that it may be placed upon a bench, pair of horses, or like supporting contrivances (not shown) so as to dispose the brake at a convenient height above the ground or floor for operating purposes.

3,481 ,174 Patented Dec. 2, 1969 Ice The brake is organized with reference to a bed or table in the form of a pair of channel-shaped rails 10 and 12 formed preferentially of aluminum extrusions and disposed in spaced parallelism as to each other.

Conceivably, a single rail of adequate dimensions could be used in lieu of the pair, of such rails.

Longitudinally-spaced C-shaped frames generically designated 'by reference character 14 are provided, each including a lower arm 16 which is so designed as to define a front side face recess 18 to which rail 10 is bolted as by bolts 20 and a rear side face recess 22 to which rail 12 is bolted as by bolts 24, the C-frames also including an upper arm 26 which overlies the lower arm in spaced relation thereto, whereby is provided an openjaw.

A lower jaw 28 in the form of a T-shaped aluminum extrusion is fixed as by bolts 30 on the upper planar surface of lower arm 16 adjacent the forward edge thereof, and a bending bar 32 in the form of an aluminum extrusion having generally the shape of the numeral 6 is hinged thereto.

One or more bending bar handle members 34 are fixed to the bending bar for facilitating movement thereof, the handle members either depending from the bending bar, as shown in FIG. 1, or extending upwardly therefrom, as shown in FIG. 1A.

Lower jaw 28 and bending bar 32 are formed with mating integral projections along their longitudinal edges, which projections are provided with openings coaxially aligned when the projections are intermeshed so that a pin 36 may be extended through the openings to complete the hinge. In this manner, bending bar 32 is hinged to lower jaw 28 along an axis.

A shiftable anvil plate 38 is provided in overlying relation to the upper planar surface of lower jaw 28 and is adjustably secured thereto by means of screws 40 which extend through elongated slots 42 in the lower jaw and are threadedly engaged in anvil plate 38.

As shown in FIG. 2, the anvil plate may be shifted rearwardly relative to the lower jaw to provide a suitable recess immediately adjacent the hinge connection between the bending bar and lower jaw, in which recess the prebent portion B of a sheet-metal workpiece W is receivable.

For the usual flat sheet-metal workpiece, as shown at X in FIGS. 3-5, the anvil plate is shifted forwardly so that its leading or forward longitudinal edge is disposed closely adjacent the aforementioned hinge connection.

A generally L-shaped floating hinge compensator 44 is provided in overlying relation to the upper planar surface of bending 'bar 32 and is pivotally secured thereto by means of spring-loaded screws 46 which extend loosely through provided openings adjacent the lower edge of the compensator and through appropriately aligned openings in the bending bar.

The innermost ends of the screws extend outwardly from the bending bar and have compression springs 48 threaded thereon in lieu of the usual securing nuts, the springs bearing at one end on the bending bar, all for purposes to appear.

Hinge compensator 44 is provided along its opposite or outermost longitudinal edge with a foot portion 50 which normally overlies and rests against the outwardly facing surface defined by the hinge connection between the bending bar and the lower jaw.

As shown in FIGS. 2 and 3, when the bending bar is in non-use position, the foot portion of the hinge compensator overlies the hinge connection and is disposed in a horizontal plane above that of the anvil plate 38.

As the bending bar is swung upwardly from the FIG. 3 position to the FIG. 4 position, the compensator pivots relative to the screws 46, with foot portion 50 thereof riding upwardly relative to the lower planar surface of the workpiece, which is clamped relative to the anvil plate by a clamping subassembly to be described.

When the workpiece has been bent to the desired angular shape, the bending bar is swung downwardly whereupon the foot portion of the compensator rides downwardly to return to its normal position wherein it overlies the hinge connection.

The clamping subassembly, generally indicated by 52, includes a clamping member 54 provided with sharp tapered lowermost front and rear edges defining a fiat clamping surface 56 which is coextensive in length and with with anvil plate 38, the clamping surface preferably having a boot 58 of suitable hard, wear-resistant material in the nature of stainless steel or the like sleeved thereon for better wearability.

Clamping member 54 is fixed at its opposite upper end as by bolts 60 to the lower surface of the outermost end of a channel-shaped pivot bar 62 which is pivoted at its opposite innermost end to upper arm 26 of each C-frame 14 as by a pivot pin 64.

A handle member 66 is linked to the pivot bar, whereby the clamping member may be moved into overlying relation to the shifta-ble anvil plate to clamp the workpiece of sheet metal against the fiat surface of the anvil plate in clamping relation as shown in FIG. 3.

Handle member 66 is pivoted along one of its edges as by a pivot pin 68 to the forward end of upper arm 26 of each C-frame 14 and is pivotally connected to pivot bar 62 by a pair of short links 70, 70 pivoted at their upper ends as at 72 to an edge of the handle member and at their lower ends as at 74 to the pivot bar.

A tension spring 76 fixed at one end to upper arm 26 and at its opposite end to pivot bar 62 spring-loads clamping subassembly 52.

Locking means, best seen in FIG. 2, is provided for releasably locking the clamping subassembly in workpiece clamping position and comprises a locking block 78 pivotally mounted at its inner end within each pivot bar 62 on the pivot pin 74 and on a pivot pin 80, each of which extends through the pivot bar.

An adjustment screw 82 threaded in locking block 78 adjacent the forward end thereof extends outwardly therefrom and has a lower end which abuts the lower wall of pivot bar 62. Rotation of the adjustment screw causes the locking block to pivot relative to the pins 74 and 80 thereby raising or lowering the block to raise or lower the position of a locking bolt 84 threaded in the block and having its head disposed upwardly of the upper planar surface of the block.

The head 86 of a screw 88 threadedly engaged in the handle member is adapted to contact the head of locking bolt 84 when the handle member is rotated in a counterclockwise direction, thereby effectively locking the clamping subassembly. Rotation of the handle member in an opposite direction unlocks the clamping subassembly.

In lieu of the locking bolt 84 and screw 88, suitable camming surfaces could be provided on the handle member and locking block to provide the same locking action.

The upper surface of the lower arm 16 of each C-frame 14 may be stepped as at 90 at measured intervals along its length, the steps being adapted to receive the inner edge of a workpiece thereagainst and being marked with suitable indicia 92 inscribed on lower arm 16 to indicate the precise location of the bend to be placed in the workpiece.

In use, a workpiece is properly positioned relative to lower arm 16 so that it rests upon anvil member 38 and foot portion 50 of hinge compensator 44, the anvil mem- 4 ber first having been positioned according to the presence of absence of a prebent portion in the workpiece.

Handle member 66 is now swung downwardly to bring clamping surface 56 of clamping member 54 into contact with the upper planar surface of the workpiece and the handle member is rotated to bring the head 86 of screw 88 into contact with the head of the locking bolt 84 provided in locking block 78, thereby effectively locking the clamping subassembly relative to the workpiece and anvil member.

Bending bar handle member 34 is now swung upwardly to cause the foot portion 50 of the compensator 44 to pivot upwardly relative to bending bar 32 thereby causing the workpiece to bend along the forward edges of the anvil plate and clamping member.

When the workpiece has been bent to the desired angle, the handle member is swung downwardly and the compensator 44 returns to its rest position.

The floating compensator makes for easier bending and will not marr the surface of the workpiece.

The brake is so designed that a plurality thereof may be coupled together as by coupling means 94, see FIG. 1, to accept workpieces of virtually any length, with reinforcing bars 96 being provided and extending between the rails 10 and 12 to impart added strength and rigidity to the composite structure.

I claim:

1. A sheet metal brake comprising:

(a) a frame having a fixed jaw and a movable jaw;

(b) an anvil member adjustably secured to said fixed (c) said movable jaw having a clamping surface movable between workpiece clamping and non-clamping positions relative to the anvil member;

(d) means for releasably locking the movable jaw in workpiece clamping position;

(e) a bending member hingedly connected to the fixed jaw; and

(f) a spring-loaded fioatable compensator pivoted to the bending member and having a surface bearing on the workpiece.

2. A sheet metal brake according to claim 1, wherein said anvil member is shiftable relative to said fixed jaw for providing a recess adjacent the hinge connection between the bending member and fixed jaw in which recess the prebent portion of a workpiece is receivable.

3. A sheet metal brake according to claim 1, wherein said fioatable compensator is pivoted to said bending member by means of screws having compression spring threaded thereon.

4. A sheet metal brake according to claim 1, including a wear-resistant boot sleeved on the clamping surface of the movable jaw.

5. A sheet metal brake according to claim 1, wherein the means for releasably locking the movable jaw in workpiece clamping position comprises, a handle pivoted to the movable jaw, a locking member On the handle and a locking member on the movable jaw.

6. A sheet metal brake according to claim 1, including stepped indentations and indicia on the fixed jaw.

References Cited UNITED STATES PATENTS 1,402,801 1/1922 Schott a- 72319 2,564,459 8/1951 Berkson 72-3 19 3,147,791 9/1964 Rauen et al. 72-3l9 3,161,223 12/1964 Marsh 72-319 X MILTON J. MEHR, Primary Examiner 

